Davis K D, Kiss Z H, Luo L, Tasker R R, Lozano A M, Dostrovsky J O
Department of Surgery, University of Toronto, Ontario, Canada.
Nature. 1998 Jan 22;391(6665):385-7. doi: 10.1038/34905.
Many amputees have a sense of their missing 'phantom' limb. Amputation can alter the representation of the body's surface in the cerebral cortex and thalamus, but it is unclear how these changes relate to such phantom sensations. One possibility is that, in amputees who experience phantom sensations, the region of the thalamus that originally represented the missing limb remains functional and can give rise to phantom sensations even when some thalamic 'limb' neurons begin to respond to stimulation of other body regions. Here we use microelectrode recording and microstimulation during functional stereotactic mapping of the ventrocaudal thalamus in amputees to determine both the responses of the neurons to stimulation of the skin and the perceptual effects of electrical activation of these neurons. Thalamic mapping revealed an unusually large thalamic stump representation, consistent with the findings from animal experiments. We also found that thalamic stimulation in amputees with a phantom limb could evoke phantom sensations, including pain, even in regions containing neurons responsive to tactile stimulation of the stump. These findings support the hypothesis that the thalamic representation of the amputated limb remains functional in amputees with phantoms.
许多截肢者会感觉到自己缺失的“幻肢”。截肢会改变大脑皮层和丘脑中身体表面的表征，但尚不清楚这些变化与这种幻肢感觉有何关联。一种可能性是，在经历幻肢感觉的截肢者中，最初代表缺失肢体的丘脑区域仍保持功能，即使一些丘脑“肢体”神经元开始对身体其他部位的刺激产生反应，也能引发幻肢感觉。在这里，我们在截肢者腹后丘脑的功能立体定向映射过程中使用微电极记录和微刺激，以确定神经元对皮肤刺激的反应以及这些神经元电激活的感知效应。丘脑映射显示丘脑残端表征异常大，这与动物实验的结果一致。我们还发现，有幻肢的截肢者丘脑刺激即使在包含对残端触觉刺激有反应的神经元的区域也能引发幻肢感觉，包括疼痛。这些发现支持了这样一种假设，即截肢肢体的丘脑表征在有幻肢的截肢者中仍保持功能。
